Method for determining the condition of the uterine isthmus



July 2, 1963 E. c. MANN ETAL 3,095,871

METHOD FOR DETERMINING THE CONDITION OF THE UTERINE ISTHMUS Filed Jan. 26, 1960 3 Sheets-Sheet 1 a $3 1} DNVENTORS p, Q q Wu C [aw/m0 6- MANN 4 g: 'gg as n: 145/4 L/flM :D. McL HEN W m $5 v wgmwyzw \N ATTORNEYS July 2, 1963 E. c. MANN ETAL 3,095,871

METHOD FOR DETERMINING THE GONDITION OF THE UTERINE I'STHMUS Filed Jan. 26, 1960 3 Sheets-Sheet 2 ATTORNEY5 y 1963 E. c. MANN ETAL 3,095,871

METHOD FOR DETERMINING THE CONDITION OF THE UTBRIINE ISTHMUS Filed Jan. 26,1960 5 Sheets-Sheet 3 T1EI-5- ATTORN EYS United States Patent 3,695,871 METHOD FOR DETERMINING THE CGNDITION OF THE UTEREIE ISTHMUS Edward C. Mann, 445 E. 68th St., New York, N.Y., and William D. McLarn, The Glen, Locust Valley, N.Y. Filed Jan. 26, 196i), Ser. No. 1,931 1 Claim. (Cl. 1282) This invention relates to a diagnostic and experimental device and method useful in determining the tone and character of the uterine isthmus as well as other characteristics of the female uterus.

FIG. 1 of the attached drawings is a diagrammatlc representation of a frontal section of the uterus;

FIG. 2 is a perspective view of a device embodied in this invention;

FIG. 3 is a partial longitudinal sectional view taken along 33 with the stylet removed showing the details of each end of a device embodied in the present invention;

FIG. 4 is a diagrammatic representation of the dynamics of the expansion of the balloon disposed in a normal uterus as the radiopaque medium is being introduced into the balloon;

FIGS. 5 and 6 are drawings of X-rays taken using the device of the present invention.

As will be seen from FIG. 1, the uterus is a hollow muscular organ having an upper portion (the corpus) having a central cavity which is triangular in shape, a smaller intermediate portion of restricted diameter (the uterine isthmus) and a lower portion (cervix) which is somewhat slightly enlarged as compared with the isthmus.

The cavities of these three sections communicate with each other, the cavity of the cervix communicating with the vagina. The boundaries of the isthmus are marked by an upper and lower opening, the lower os (histologic internal 0s) and the superior os (anatomical internal os) respectively.

It was previously thought that the isthmus served no other function than reserve space for accommodating the foetus as it developed in the uterus. The function of retaining the foetus within the uterus was ascribed to the constrictive muscular action (sphincter action) of the cervix. More recently, however, it has been found that, on the contrary, the more important agency for retaining the foetus in the uterus during development is the sphincter action of the isthmus. The ability of the isthmus to function properly as a sphincter depends on tone of the muscle forming its walls.

One of the causes for habitual abortion in women is a defect in the tone of the muscle of the isthmus (abnormal isthmic hypotonia). In this condition the muscle is not in its proper state of contraction so that it may not properly perform its sphincter function. However, no satisfactory means or method has been available in the prior art for diagnosing this condition in a non pregnant uterus.

In addition to the above mentioned condition, there are many situations wherein it is important to determine the tone and length of the uterine isthmus in vivo. Thus for example it is known that both the tone and length of the isthmus vary during the various phases of the menstrual cycle. Furthermore, patients suffering from primary dysmenorrhea do not exhibit a relaxed isthmus in the early phases of menstruation which is characteristic of normal menstruation. Moreover, in certain cases of infertility there is a demonstratable spasticity of the isthmus at the time of ovulation. A device which is capable of accurately determining the muscular tone of the isthmus would be a useful diagnostic tool in diagnosing these conditions.

Various efforts have been made in the prior art to provide a proper diagnostic tool for measuring the tone of the uterine isthmus. Thus for example the isthmus has been outlined from above by introducing radiopaque liquid into the uterine cavity with a needle through the cul-de-sac after which an X-ray is taken to view the condition of the organ. While this is superior to other prior art methods, the retrograde egress of dye through the isthmus under the influence of gravity does not make it possible to develop sufficient pressure within the uterus to accurately test the sphincteric tone of the isthmus.

Others have described a method entailing the use of vari-sized balloons attached to the tip of a metal cannula. Depending upon the estimated size of the uterine cavity, a smaller or larger balloon is introduced into the uterus. An aqueous medium by way of a syringe attached to the metal catheter is then forced into the intrauterine balloon. After the balloon is filled and has assumed the shape of the uterus, an X-ray film is taken. Downward traction is then exerted on the metal cannula and, as small amounts of radiopaque materials are successively withdrawn, the balloon is pulled through the isthmus and cervix during the course of which serial X-rays are taken. This method is extremely gross involving as it does such unmeasured variables as traction and pressure.

A device and method have now been produced which serve the various purposes outlined above and overcome the objectional features of the prior art.

It is accordingly an object of the present invention to provide a device which is useful in measuring the tone and length of the uterine isthmus for diagnostic and experimental purposes.

It is a further object of the present invention to provide a method for measuring the tone and length of the uterine isthmus for diagnostic and experimental purposes.

Other and more detailed objects will be apparent from the following description and attached drawings.

Referring to FIGS 2 and 3 of the drawings, 2 is a latex balloon having a latex neck 4 which is joined to a hard rubber non-expansile catheter shown generally at 6. The neck 4 is joined to catheter 6 in any suitable manner. In the embodiment illustrated thread 8 is wound around neck 4 and the balloon end of catheter 6.

Catheter 6 comprises four distinct sections. Section 10 is adjacent neck 4 of the balloon and is of slightly greater diameter than section 12 which follows. The walls of the catheter 6 at section 10' are relatively thick and the opening 18 is relatively small. This serves to prevent the expansion of section 10 when balloon 2 is inflated.

Section 12 is the longest section of the catheter and may vary in length. Section 12 of catheter 6- enlarges to the back end of the device to form another enlarged portion 14 which has walls that are thicker than those of section 12. Section 14 of the catheter in turn enlarges into section 16 which is the hub portion of catheter 6. Section 16 is contoured to accommodate a hub 20 which is fitted into the back end of catheter 6.

Hub 20 is formed with a plurality of protuberances 22 which serve to secure it into section 16 of the catheter. To further secure section 16 to hub 20 securing means 24 made of thread or similar material is wound around section 16 and hub 20* as indicated in the drawings.

A stylet 26 comprising a long wire and a looped end 28 is inserted through the opening in hub 20' into the catheter 6 and balloon 2. This serves to facilitate the introduction of the balloon into the uterus.

In use with the aid of the stylet the enlarged portion of the balloon is introduced into the cavity of'the corpus of the uterus and the neck of the balloon into the isthmus. Radiopaque medium is introduced into the catheter and balloon through hub 20. After the necessary amount of material is introduced into the uterus, an X-ray is taken to determine the condition of the various parts of the uterus.

The dynamics of the expansion of the balloon disposed in a normal uterus as described above as the radiopaque medium is being introduced into the balloon are described in connection with FIG. 4.

In A, the balloon is in the process of being inflated with radiopaque material. As this media is injected into the balloon, the pressure rises sharply until the resistance of the rubber is overcome at'approximately 200 mm. Hg. This results in sudden inflation of the balloon and a corresponding abrupt drop in intraluminal pressure (B). This is characteristic of the inflation of a rubber balloon and is not unique in this device. With continuation of the injection the balloon continues to increase in volume until it fills the endometrial cavity. As the balloon fills the cavity and adapts to its contours there is a progressive increase in pressure. A second critical point in pressure (C) is reached when the enlarging balloon encounters myometrial resistance (resistance due to the muscular walls of the cavity of the uterus) suflicient to cause the latex neck of the balloon to inflate below the level of the anatomic internal os. Again there is a drop in pressure (D). Further injection results in expansion of the latex neck within the isthmus and upper cervix. With increased intra-isthmic and endocervical resistance, expansion progresses downward, culminating in protrusion of the latex neck through the external as (E).

The operation of the present device which makes it possible to outline the isthmus and the endocervical canal is dependent on a two-stage expansion principle. Thus with an increase of pressure inside the balloon due to the resistance otfered by the walls of the uterus a critical pressure is reached (which depends on the ratio in diameters between balloon and balloon neck) at which point the intraisthmic portion of the balloon undergoes a secondary expansion to outline the isthmus and the endocervical canal. This makes it possible not only to delineate the isthmus and the cervix but also to study the changes of the endocervical and isthmic caliber under various controlled pressures.

In order to obtain the two-stage expansion of the balloon the dimensions of the device must be maintained within certain limits. The more critical dimensions of the device are the relative sizes of the transverse diameter of the balloon, the length of the neck, and the diameter of the neck. In general these are maintained in a ratio in the range of about 51620.5 to :825. In a preferred embodiment of this invention the'transverse diameter of the balloon is 6 mm., the length of the neck is 7 mm., the diameter of the neck is 1.6 mm., and the thickness of the latex used to make the balloon and neck is .012 inch.

The remaining dimensions of the present device are not as critical as those outlined above but are important in determining the various characteristics of the device and the use to which it is to be put. Thus the outside dimension of section 10 may vary from 2.0 to 3.5 mm. The diameter of opening 18 of section 10may vary from .4 to .8 mm. The outside diameter of section 12 may vary from 1.5 to 2.5 mm. Whereas the inside diameter may vary from .4 to .8 mm. The outside diameter of section 14 may also vary from 2 to 4 mm. whereas the by the inventors on over 500 non-pregnant women. The 6 two-stage expansion principle has been applied to a variety of intrauterine balloon models with different ratios between diameters of the balloon and balloon neck. Thus an increase in the diameter'of the balloon neck reduces the critical pressure at which secondary expansion within the isthmus occurs and, inversely, a decrease in the diameter of the balloon neck increases the critical pressure necessary for secondary expansion. The differential gradient of expansion can, accordingly, be altered depending upon the degree of intrauterine or intraisthmic pressure desired. This in turn depends upon the diagnostic or research use to which the balloon is being put.

FIG. 5 demonstrates by way of the two-stage intrauterine balloon the appearance of the normal isthmus. Note the constricted isthrnic segment between the uterus above and cervix below. This typical hour glass configuration is due to sphincteric activity of the isthmic segment. In the normal individual the muscular isthmus maintains its tone and does not increase its caliber even in the face of extreme intraisthmic pressures. The fibrous cervix, on the other hand, is much more distensible and is much less effective as a sphincter.

FIG. 6 demonstrates the typical appearance of an isthmus with impaired sphincteric ability. Note that the isthmus is as distensible as the fibrous cervix and that the normal hour-glassing is gone. Clinical follow-up of individuals with isthmic hypotonia of this order correlates with the development .of cervical incompetence which, in the absence of surgery, leads to. miscarriage in pregnancy.

-While the invention has been described with particular reference to specific embodiments, it is to be understood that it is not limited thereto, but is to be construed broadly and restricted solely by the scope of the appended claim.

What is claimed is:

A method for diagnosing the condition of the uterine isthmus which comprises, providing an expandable unit adapted for primary expansion to a critical pressure and secondary expansion beyond said critical pressure, inserting said expandable unit into the cervical canal, uterine isthmus and the cavity of the corpus of the uterus, introducing a radiopaque fluid into said expandable unit whereby it is subjected to a primary expansion and occupies the corpus of the'uterus, continuing the introduction of said liquid beyond a critical pressure whereby a secondary expansion of said expandable unit is caused to take place and occupies and outlines the uterine isthmus and cervical canal, and taking an X-ray film of the uterus, uterine isthmus and cervical canal while said expandable unit is in position within said uterus, uterine isthmus and cervical canal and is under condition of primary and secondary expansion.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Article by Honor-Srnathers in Archives of Surgery, October 1947, pages 498-504. Copy in Division 55.) 

